Heat exchanger assembly

ABSTRACT

A heat exchanger includes an inlet manifold and an outlet manifold. A plurality of heat exchanger tubes are in fluid communication with the inlet manifold at a first end portion and the outlet manifold at a second end portion. The outlet manifold fluidly connects outlets on each of the plurality of heat exchanger tubes. A plurality of fluid conduits are in fluid communication with and extending from the outlet manifold. The plurality of fluid conduits are longitudinally spaced along the outlet manifold and are in fluid communication with a common outlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/898,706, which was filed on Sep. 11, 2019 and is incorporated herein by reference.

BACKGROUND

The present disclosure relates to air conditioner, heat pump and refrigeration applications and, more particularly, to heat exchangers used in those systems.

Buildings, such as university buildings, office buildings, residential buildings, commercial buildings, and the like, include climate systems which are operable to control the climate inside the building. A typical climate system includes an evaporator, a compressor, a condenser, and an expansion valve. These components utilize a refrigerant to maintain an indoor temperature of the buildings at a desired level.

SUMMARY

In one exemplary embodiment, a heat exchanger includes an inlet manifold and an outlet manifold. A plurality of heat exchanger tubes are in fluid communication with the inlet manifold at a first end portion and the outlet manifold at a second end portion. The outlet manifold fluidly connects outlets on each of the plurality of heat exchanger tubes. A plurality of fluid conduits are in fluid communication with and extending from the outlet manifold. The plurality of fluid conduits are longitudinally spaced along the outlet manifold and are in fluid communication with a common outlet.

In a further embodiment of any of the above, the plurality of conduits include a common internal diameter defining a single passageway.

In a further embodiment of any of the above, the plurality of conduits include varying internal diameters defining a single passageway.

In a further embodiment of any of the above, the plurality of conduits are unevenly spaced longitudinally along the outlet manifold.

In a further embodiment of any of the above, the plurality of conduits are arranged perpendicular to the plurality of heat exchanger tubes.

In a further embodiment of any of the above, a collector pipe is spaced from the outlet manifold. The plurality of conduits are attached to the outlet manifold at a first end and the collector pipe at a second end.

In a further embodiment of any of the above, the plurality of conduits are located inward from opposing ends of the collector pipe.

In a further embodiment of any of the above, the plurality of conduits are arranged perpendicular to the plurality of heat exchanger tubes.

In a further embodiment of any of the above, the outlet manifold includes a first length in a longitudinal direction of the outlet manifold. The collector pipe includes a second length in a longitudinal direction of the collector pipe. The second length is greater than the first length.

In a further embodiment of any of the above, the common outlet is in fluid communication with an outlet pipe. The outlet pipe is spaced inward from opposing ends of the collector pipe.

In a further embodiment of any of the above, the inlet manifold includes a distribution insert that has a plurality of distribution outlets longitudinally spaced from each other within the inlet manifold.

In a further embodiment of any of the above, the plurality of distribution outlets on the distribution insert include at least one pair of adjacent distribution outlets fluidly separated by a partition.

In a further embodiment of any of the above, a plurality of fins are attached to an exterior surface of each of the plurality of heat exchanger tubes.

In another exemplary embodiment, a method of distributing a refrigerant through a heat exchanger includes the step of directing refrigerant through an inlet manifold. The refrigerant is directed from the inlet manifold into a plurality of heat exchanger tubes. The refrigerant from the heat exchanger tubes is directed into an outlet manifold. The refrigerant from the outlet manifold is directed into a plurality of fluid conduits in fluid communication with and extending from the outlet manifold. The plurality of fluid conduits are longitudinally spaced along the outlet manifold and are in fluid communication with a common outlet.

In a further embodiment of any of the above, the plurality of conduits are unevenly spaced longitudinally along the outlet manifold.

In a further embodiment of any of the above, a collector pipe is spaced from the outlet manifold. The plurality of conduits are attached to the outlet manifold at a first end and the collector pipe at a second end.

In a further embodiment of any of the above, the plurality of conduits are located inward from opposing ends of the collector pipe.

In a further embodiment of any of the above, the refrigerant is directed through an outlet pipe in fluid communication with the common outlet and spaced inward from opposing ends of the collector pipe.

In a further embodiment of any of the above, the refrigerant is directed through the inlet manifold. The refrigerant is directed through a distribution insert that has a plurality of distribution outlets longitudinally spaced from each other within the inlet manifold.

In a further embodiment of any of the above, the plurality of distribution outlets on the distribution insert include at least one pair of adjacent distribution outlets fluidly separated by a partition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example refrigerant system.

FIG. 2 illustrates an example heat pump system.

FIG. 3 illustrates an example heat exchanger for use in either the system of FIG. 1 or FIG. 2.

FIG. 4 illustrates an enlarged view of a portion of the heat exchanger of FIG. 3.

FIG. 5 illustrates another example outlet manifold in fluid communication with a collector pipe for use in the heat exchanger of FIG. 3.

FIG. 6 is a schematic cross-sectional view of the example outlet manifold with the collector pipe along line 6-6 of FIG. 5.

FIG. 7 illustrates another example heat exchanger.

FIG. 8 illustrates yet another example heat exchanger.

DETAILED DESCRIPTION

A basic refrigerant system 20 is illustrated in FIG. 1 and includes a compressor 22 delivering refrigerant into a discharge line 23 leading to a heat exchanger 24, such as a condenser for subcritical applications and a gas cooler for trans-critical applications. The heat is transferred in the heat exchanger 24 from the refrigerant to a secondary loop fluid, such as ambient air, with a fan 27. The high pressure, but cooled, refrigerant passes into a refrigerant line 25 downstream of the heat exchanger 24 and through an expansion device 26, where it is expanded to a lower pressure and temperature. Downstream of the expansion device 26, the refrigerant flows through an evaporator 28 and back to the compressor 22. A fan 29 draws air to be conditioned through the evaporator 28.

This basic configuration can be used in a number of applications, such as in residential systems and in rooftop systems. When used with a residential system, the evaporator 28 is located inside a residence and the fan 29 draws air through the evaporator 28. Additionally, the fan 29 may be associated with a separate heating system for the residence.

When used with a roof top system, the refrigerant system 20 is located on a rooftop or an exterior of a building. In this configuration, refrigerant system 20 includes an indoor section that draws air from inside the building and conditions it with the evaporator 28 and directs the air back into the building. Additionally, the refrigerant system 20 for the rooftop application would include an outdoor section with the fan 27 drawing ambient air through the heat exchanger 24 to remove heat from the heat exchanger 24 as described above.

FIG. 2 illustrates another type of refrigeration system, such as a heat pump 30, capable of operating in both cooling and heating modes. The heat pump 30 includes a compressor 32. The compressor 32 delivers refrigerant through a discharge port 34 that is returned back to the compressor through a suction port 36.

Refrigerant moves through a four-way valve 38 that can be switched between heating and cooling positions to direct the refrigerant flow in a desired manner (indicated by the arrows associated with valve 38 in FIG. 2) depending upon the requested mode of operation, as is well known in the art. When the valve 38 is positioned in the cooling position, refrigerant flows from the discharge port 34 through the valve 38 to an outdoor heat exchanger 40 where heat from the compressed refrigerant is rejected to a secondary fluid, such as ambient air. A fan may be used in associate with the outdoor heat exchanger 40.

The refrigerant flows from the outdoor heat exchanger 40 through a first fluid passage 46 into an expansion device 42. The refrigerant when flowing in this forward direction expands as it moves from the first fluid passage 46 to a second fluid passage 48 thereby reducing its pressure and temperature. The expanded refrigerant flows through an indoor heat exchanger 44 to accept heat from another secondary fluid and supply cold air indoors. A fan may be associated with the indoor heat exchanger 44. The refrigerant returns from the indoor exchanger 44 to the suction port 36 through the valve 38.

When the valve 38 is in the heating position, refrigerant flows from the discharge port 34 through the valve 38 to the indoor heat exchanger 44 where heat is rejected to the indoors. The refrigerant flows from the indoor heat exchanger 44 through second fluid passage 48 to the expansion device 42. As the refrigerant flows in this reverse direction from the second fluid passage 48 through the expansion device 42 to the first fluid passage 46, the refrigerant flow is more restricted in this direction as compared to the forward direction. The refrigerant flows from the first fluid passage 46 through the outdoor heat exchanger 40, four-way valve 38 and back to the suction port 36 through the valve 38.

FIG. 3 illustrates an example heat exchanger 60. The heat exchanger 60 could be used in the refrigerant system 20 as the heat exchanger 24 or the evaporator 28 or with the heat pump 30 in place of the outdoor heat exchanger 40 or the indoor heat exchanger 44. The heat exchanger 60 includes an inlet manifold 62 fluidly connected to an outlet manifold 78 through a plurality of heat exchanger tubes 70.

The inlet manifold 62 receives refrigerant from a distribution insert 64 that extends through a partition fitting 65 at a first end of the inlet manifold 62 and extends towards a second end opposite end of the inlet manifold 62. The distribution insert 64 includes a plurality of distribution outlets 66 that allow the refrigerant to flow from distribution insert 64 into the inlet manifold 62. A plurality of partitions 68 are located within the inlet manifold 62 and separate the distribution outlets 66 from an adjacent distribution outlet 66 or from adjacent groups of distribution outlets 66. The number and density of distribution outlets 66 located between adjacent partitions can vary depending on the operating conditions of the heat exchanger 60 to control refrigerant flow into the plurality of heat exchanger tubes 70.

As shown in FIGS. 3 and 4, a first end portion 72 of the plurality of heat exchanger tubes 70 extends from the inlet manifold 62 towards a second end portion 74 of the plurality of heat exchanger tubes 70 at the outlet manifold 78. In the illustrated example, the arrangement of the plurality of heat exchanger tubes 70 includes a width of between approximately three feet (91 cm) and six feet (182 cm) and a height of between approximately three feet (91 cm) and four feet (122 cm). The plurality of heat exchanger tubes 70 are flat tubes such that opposing longitudinal sides 73 are generally flat and connected by rounded end portions 75. By shaping the plurality of heat exchanger tubes 70 in this configuration, an external surface of the plurality of heat exchanger tubes 70 is increased compared to an internal cross-sectional area to improve heat transfer between the refrigerant passing through the plurality of heat exchanger tubes 70 and a secondary fluid, such as air.

Additionally, when the plurality of heat exchanger tubes 70 are flat tubes, the flat tubes may be formed to include a plurality of channels, or internal passageways that are much smaller than the internal passageways of the tubes in the conventional round-tube plate-fin heat exchanger. In this disclosure, the flat tubes may also comprise mini size multi-port channels, or micro size multi-port channels (otherwise known as microchannel tubes). Hence the flat tube heat exchangers using small size multi-port channels are alternately known as Microchannel Heat Exchanger (FIG. 4) in the art. However, in other constructions of the flat tubes may include one channel, or internal passageway.

Furthermore, the opposing longitudinal sides 73 of the heat exchanger tubes 70 are connected to cooling fins 76 that form a plurality of secondary heat transfer surfaces. In the illustrated example, the cooling fins 76 are arranged in a continuous “W” or serpentine pattern with louvers with turns in the cooling fins 76 being in contact with adjacent ones of the plurality of heat exchanger tubes 70 to improve heat transfer from the refrigerant in the plurality of heat exchanger tubes 70 and the secondary fluid. The cooling fins 76 encompass the width of the heat exchanger tube 70 which also defines the minor dimension of the microchannel heat exchanger and through which the air flows. The cooling fins 76 are positioned along the heat exchanger tubes 70 and solidly coupled to two adjacent flat tubes by a brazing or welding process. Additionally, in the illustrated example, a direction of flow of the refrigerant through the plurality of heat exchanger tubes 70 is generally perpendicular to a direction of flow of the secondary fluid over the heat exchanger tubes 70. However, other configurations of heat exchanger tubes 70 could be utilized with this disclosure.

Once the refrigerant reaches the second end portions of the plurality of heat exchanger tubes 70, the refrigerant is directed into the outlet manifold 78. The outlet manifold 78 collects the refrigerant from each of the plurality of the heat exchanger tubes 70 and directs the refrigerant into one of a plurality of conduits 80. The outlet manifold 78 also allows for fluid communication between outlets of the plurality of heat exchanger tubes 70 such that refrigerant can travel along a length of the outlet manifold and in a direction generally perpendicular to a length of the heat exchanger tubes 70. In the illustrated example, there are five conduits 80 evenly longitudinally spaced a distance D1 from each other along the outlet manifold 78.

Alternatively, the conduits 80 could be unevenly spaced such that larger amounts of refrigerant could be removed from specific longitudinal positions of the outlet manifold 78 depending on operating conditions of the system incorporating the heat exchanger 60. Furthermore, a diameter of the conduits 80 could vary along the outlet manifold 78 while the conduits 80 remained evenly spaced along the longitudinal direction of the outlet manifold 78. Additionally, at least one of the conduits 80 includes a length that is 1 to 25 times larger than a diameter of the conduits 80 and the outlet manifold 78 includes a diameter 1 to 20 times a diameter of the at least one of the conduits 80.

In the illustrated example, the fluid conduits 80 are round tubes with a single passageway there through and without external heat transfer features, such as cooling fins. The fluid conduits 80 are also spaced from a flow of a secondary cooling fluid with 10-25 heat exchanger tubes 70 to each fluid conduit 80. In another example, there are 15 heat exchanger tubes 70 for each fluid conduit 80.

One feature of allowing the refrigerant to leave the outlet manifold 78 through the conduits 80, instead of conduit internal to manifold 78, is a much lower pressure drop penalty while achieving uniformity of pressure field within the outlet manifold 78. One feature of the conduit network, either internal or external, is to avoid non-uniformity of the pressure field inside the manifold 78 at lowest possible pressure loss incurred by the fluid conduits 80 themselves.

When using an internal conduit in a manifold, the refrigerant from the heat exchanger tubes enters the internal conduit through a set of ports that are disposed on the body of the internal conduit and in the process incurs pressure loss which is almost negligible in the external conduit. Also, when using the internal conduit, the hydraulic diameter of the conduit housed inside manifold 78 is inherently limited due to lack of available spacing. This leads to higher velocities inside the internal conduit leading to very high resistance and pressure drop losses which scale by power of two of the average refrigerant velocities.

In comparison, the fluid conduits 80 are not restricted to small diameters and facilitates larger flow cross-sectional areas leading to lower overall refrigerant velocities and hence comparatively low pressure drop losses. It should be noted that the internal distributor 64 that is used in the inlet manifold 62 also incurs high pressure drop but this pressure drop does not affect the system performance negatively since it constitutes an extension and part of the expansion device 26 pressure drop. In the case of the outlet manifold 78, the situation is thermodynamically opposite and any pressure loss from the point where the refrigerant exits heat exchanger tubes 74 till it enters the compressor 22 via any network of piping will adversely impact compressor power consumption and hence system efficiency. The lower the absolute pressure at the compressor 22 inlet, the more work the compressor 22 has to perform in order to discharge high pressure vapor at its outlet which is fixed by the condenser 24 to a predetermined value. Therefore, one feature of any distribution system that is used at the outlet manifold 78 between points where refrigerant exits heat exchanger tubes 74 up to the common exit 82 is a minimum possible pressure drop loss while yielding highly uniform pressure field inside the outlet manifold 78. The reduction in pressure drop resulting from the reduction in flow resistance helps improve the overall efficiency of the refrigeration system.

The refrigerant passing through the conduits 80 travels to a common outlet 82. In the illustrated example, the refrigerant passing through the conduits 80 is connected to the common outlet 82 through a plurality of T-fittings 84 interconnecting the conduits 80 with transfer tubes 86.

FIGS. 5 and 6 illustrate another example outlet manifold 78A similar to the outlet manifold 78 except where described below or shown in the Figures. The second end portions 74 of the plurality of heat exchanger tubes 70 are in fluid communication with the outlet manifold 78A. After the refrigerant passes from the plurality of heat exchanger tubes 70 and into the outlet manifold 78A, the refrigerant is directed from the outlet manifold 78A into conduits 80A longitudinally spaced along the outlet manifold 78A. The spacing between two adjacent conduits 80A could range from 1 to 20 times the outer diameter of the outlet manifold 78A.

In the illustrated example, the conduits 80A are arranged perpendicular or transverse to a longitudinal direction of the plurality of heat exchanger tubes 70. Alternatively, the conduits 80A could be positioned such that the conduits 80A are parallel to the longitudinal direction of the plurality of heat exchanger tubes 70. In one example, the conduits 80A are 50 mm (1.97 inches) plus or minus 10 mm (0.39 inches) in length. In yet another example, at least one of the conduits 80A includes a length that is 1 to 25 times larger than a diameter of the conduits 80A.

Once the refrigerant passes through the conduits 80A, it enters a collector pipe 90A. The collector pipe 90A collects the refrigerant from each of the conduits 80A and directs the refrigerant to an outlet 82A through an outlet tube 88A. In the illustrated example, the outlet tube 88A extends from a middle region of the collector pipe 90A and in a direction parallel with the plurality of heat exchanger tubes 70 with a turn to the outlet 82A that is generally parallel to the longitudinal direction of the collector pipe 90A. However, other orientations are possible. Additionally, as shown in FIG. 5, a length DOM of the outlet manifold 78A is greater than a length DCP of the collector pipe 90A.

As shown in FIG. 6, the outlet manifold 78A extends along a longitudinal axis OM and the collector pipe 90A extends along a longitudinal axis CP that is generally parallel to the longitudinal axis OM. The conduits 80A extend along a longitudinal axis C that intersects the longitudinal axis CP. The longitudinal axis C is offset by a distance O1 from the longitudinal axis OM such that the conduits 80A intersect a central region of the collector pipe 90A but are spaced from a central region of the outlet manifold 78A. One feature of the configuration shown in FIGS. 5 and 6 is a reduction in pressure drop across at least one of the outlet manifold 78A, conduits 80A, and the collector pip 90A experienced by the refrigerant due to a reduction in flow resistance relative to prior art internal distributor designs. The reduction in pressure drop resulting from lower flow resistance helps maintain high suction pressures at compressor 22 inlet leading to improved system efficiency and uniformity of pressure field in outlet manifold 78A improves refrigerant distribution and hence heat transfer between the heat exchanger 60 and the secondary fluid.

FIG. 7 illustrates another example heat exchanger 160 similar to the heat exchanger 60 except where described below or shown in the Figures. The heat exchanger 160 includes the inlet manifold 62 in fluid communication with a first end portion 172 of a first plurality of heat exchanger tubes 170 and a ribbon bend 175 in fluid communication with a second end portion 174 of the first plurality of heat exchanger tubes 170. The ribbon bend 175 is in fluid communication with a first end portion 179 of a second plurality of heat exchanger tubes 177 and a second end portion 181 of the second plurality of heat exchanger tubes 177 is in fluid communication with the outlet manifold 78. In the illustrates example, the first plurality of heat exchanger tubes 170 extend in a parallel but opposite direction from the second plurality of heat exchanger tubes 177. Additionally, the first plurality of heat exchanger tubes 170 are longer in length than the second plurality of heat exchanger tubes 177. Furthermore, the first and second plurality of heat exchanger tubes 170, 177 include cooling fins 76 while the ribbon bend 175 does not include any of the cooling fins 76.

FIG. 8 illustrates another example heat exchanger 260 similar to the heat exchanger 60 except where described below or shown in the Figures. The heat exchanger 260 includes an inlet manifold 262 in fluid communication with a first end portion 272 of a first plurality of heat exchanger tubes 270 and a second end portion 274 of the heat exchanger tubes 270 in fluid communication with an outlet manifold 278. The inlet and outlet manifolds 262, 278 are similar to the inlet and outlet manifolds 62, 78, respectively, but include multiple bends or turns that form a generally square or rectangular opening. The inlet manifold 262 can include at least one inlet 264 and the outlet manifold 278 can include at least one outlet 282. In the illustrated example, the inlet manifold 262 includes one inlet 264 at each end and the outlet manifold 278 includes one outlet 282 at each end.

Although the different non-limiting examples are illustrated as having specific components, the examples of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting examples in combination with features or components from any of the other non-limiting examples.

It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claim should be studied to determine the true scope and content of this disclosure. 

What is claimed is:
 1. A heat exchanger comprising: an inlet manifold; an outlet manifold; a plurality of heat exchanger tubes in fluid communication with the inlet manifold at a first end portion and the outlet manifold at a second end portion, wherein the outlet manifold fluidly connects outlets on each of the plurality of heat exchanger tubes; and a plurality of fluid conduits in fluid communication with and extending from the outlet manifold, wherein the plurality of fluid conduits are longitudinally spaced along the outlet manifold and in fluid communication with a common outlet.
 2. The heat exchanger of claim 1, wherein the plurality of conduits include a common internal diameter defining a single passageway.
 3. The heat exchanger of claim 1, wherein the plurality of conduits include varying internal diameters defining a single passageway.
 4. The heat exchanger of claim 1, wherein the plurality of conduits are unevenly spaced longitudinally along the outlet manifold.
 5. The heat exchanger of claim 1, wherein the plurality of conduits are arranged perpendicular to the plurality of heat exchanger tubes.
 6. The heat exchanger of claim 5, further comprising a collector pipe spaced from the outlet manifold, wherein the plurality of conduits are attached to the outlet manifold at a first end and the collector pipe at a second end.
 7. The heat exchanger of claim 6, wherein the plurality of conduits are located inward from opposing ends of the collector pipe.
 8. The heat exchanger of claim 7, wherein the plurality of conduits are arranged perpendicular to the plurality of heat exchanger tubes.
 9. The heat exchanger of claim 7, wherein the outlet manifold includes a first length in a longitudinal direction of the outlet manifold and the collector pipe includes a second length in a longitudinal direction of the collector pipe and the second length is greater than the first length.
 10. The heat exchanger of claim 9, wherein the common outlet is in fluid communication with an outlet pipe and the outlet pipe is spaced inward from opposing ends of the collector pipe.
 11. The heat exchanger of claim 1, wherein the inlet manifold includes a distribution insert having a plurality of distribution outlets longitudinally spaced from each other within the inlet manifold.
 12. The heat exchanger of claim 11, wherein the plurality of distribution outlets on the distribution insert include at least one pair of adjacent distribution outlets fluidly separated by a partition.
 13. The heat exchanger of claim 1, further comprising a plurality of fins attached to an exterior surface of each of the plurality of heat exchanger tubes.
 14. A method of distributing a refrigerant through a heat exchanger comprising the steps of: directing refrigerant through an inlet manifold; directing the refrigerant from the inlet manifold into a plurality of heat exchanger tubes; directing the refrigerant from the heat exchanger tubes into an outlet manifold; and directing the refrigerant from the outlet manifold into a plurality of fluid conduits in fluid communication with and extending from the outlet manifold, wherein the plurality of fluid conduits are longitudinally spaced along the outlet manifold and in fluid communication with a common outlet.
 15. The method of claim 14, wherein the plurality of conduits are unevenly spaced longitudinally along the outlet manifold.
 16. The method of claim 14, further comprising a collector pipe spaced from the outlet manifold, wherein the plurality of conduits are attached to the outlet manifold at a first end and the collector pipe at a second end.
 17. The method of claim 16, wherein the plurality of conduits are located inward from opposing ends of the collector pipe.
 18. The method of claim 17, further comprising directing the refrigerant through an outlet pipe in fluid communication with the common outlet and spaced inward from opposing ends of the collector pipe.
 19. The method of claim 14, wherein directing the refrigerant through the inlet manifold includes directing the refrigerant through a distribution insert having a plurality of distribution outlets longitudinally spaced from each other within the inlet manifold.
 20. The method of claim 19, wherein the plurality of distribution outlets on the distribution insert include at least one pair of adjacent distribution outlets fluidly separated by a partition. 